Producing hydrogen and apparatus therefor.



C. BOSCH. PRODUCING HYDROGBN AND APPARATUS THBREPOR.

APPLICATION @AED JULY 7, 1913.

Patented July 7, 191% :2222:: NN 22222: fn :222222 e 222222 l 7 9 2 nl LN .m

1 G. BOSCH. PRODUGING HYDROGEN AND APPARATUS THBREFOR.

APPLICATION FILED JULY 7,1913. l 1 0%,7 l 6. Patented July 7, 1914;

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CARL BOSCH, OF LUDWIGSHAFEN-ON-THE-BHINIL GERMANY, ASSIGNOR TO BADISCHEANILIN & SODA FABRIK, OF LUDWIGSHAFEN QN-THE-RHINE, GERMANY, A COR-PORATION 0F BADEN.

PRODUCING HYDROGEN AND APPARATUS THERE-FOB.

Specification of Letters Patent.

Application filed July 7, 1913. Serial No. 777,740.

To all whom, it may concern:

Be it known that I, CARL Bosorr, citizen of the German Empire, residingat LudWigS hafenon-the-Rhine, Germany, have invented new and usefulImprovements in Producing Hydrogen and Apparatus Therefor, of which thefollowing is a specification.

My invention relates to a process and apparatusfor the production ohydrogen on a technical scale.

It is well known that hydrogen can be obtained by alternately passingsteam over red-hot iron and vthen reducln the iron oxid formed by meansof a re ucing gas. For instance, Giiiard, in the Moniteur Scientifique,1873, page 157, states that he produces hydrogen by alternately passinga mixture of carbon monoxid and nitrogen, prepared from air and coke,through a furnace containing iron oxid until the oxid is reduced toiron, and then passing steam over the iron, whereby hydrogen is producedand the iron is converted again into its oxid, whereupon thecycle ofoperations is re'- peated. Further, Lewes, in the specifica'- tion ofBritish Patent No. 20,752/90 describes a particular method of carryingout this process. According to the method described in thisspecification, hydrogen is obtained by the decomposition of steam bycontact with heated iron and the resulting iron oXid is reduced forre-use to the metallic state by subjecting it to the action of areducing gas. The reducing gas is prepared by passing air overred-hotcoke, andthe heat generated by the production of the reducing gas isutilized to maintain the iron and the resulting oxid at a suiiicientlyhigh temperature for the reactions to takeplace, the furnace containingthe iron and iron oxid being situated inside the coke-containinggenerator. Further, Hills and Lane, in the specification of BritishPatent No. 10,356/03 claim a process for the production of hydrogen gasconsisting in its essen@ tial features of the alternate oxidation ofmetal by steam and its deoxidation and restoration to chemical activityby crude gas,

such as water-gas, coal gas, or other gasesy generated from carbonaceousfuel. According to the processes hitherto known, some maintain the heatin the reaction furnace by applying heat by combustion, either verydiiiicult if not practically impossible to avoid local over-heatin with4the disadvantageous result that t e contents of the furnace melt to someextent and incomplete reduction takes place. Another known processconsists in employing hot reaction gases of such a temperature that afurther heatin of the reaction furnace is unnecessary, an for thispurpose the hot crude generator gases are passed directly to thereaction furnace, heating this up and reducing the iron, While theexcess of gases leaving the furnace are mixed with air and burnt 1n aregenerator through which steam is subsequently passed in the reversedirection on its way to the reaction chamber (see German Patent No.77,350). This process presents the great disadvantage that .theimpurities contained in the generator gases clog the reaction mass andcause it to melt owing to the formation of iron silicate and also thegenerator gases contain sulfur and form iron suld and sulfuretedhydrogen. For these reasons this process has hitherto not met withcommercial success. A further process described in German Patent No.95,070 consists in causing the purified generator gas or the steam onits way to the reaction furnace to be preheated on the countercurrentprinciple by the gases leaving the furnace, but this process also hasnot attained practical or commercial success by reason of the quantityoi heat contained in the gases leaving the furnace not being sufiicientto preheat the entering gases to the degree required.

I have now discovered that I can overcome the diiiicultiesanddisadvantages referred to and obtain hydrogen successfully on acommercial scale by employing purlfied reducinggas and by passing boththe said purified reducing gas and the steam through regenerators whichare situated outside the furnace containing the ferruginous mass andemploying the reducing gas which leaves the furnace for heating up theregenerators by burning it with oxygen, either as such or in the form ofair, in the said regenerators. By carryinor out the process in this way,I am enabled to prevent impurities from entering the reaction gas may beused which, from its method of production, is already in such'a suitablypure condition that 1t may be employed directly for reduction of theiron oxid without its rendering the contents of the furnace inoperativetoo quickly. f A specific method of effecting the alternate oxidationand reduction of iron according to my invention consists in employingone furnace containing the iron in conjunction with two preheaterfurnaces, for instance of the Cowper type, and this combination offurnaces can be used as follows: Assuming the iron in a cylindricaloxidation and reduction furnace to be in the oxidized state and thefirst regenerator is at a high temperature, purified reducing gas ispassed through the first rcgenerator and then through the vesselcontaining the iron oxid from the top to the bottom, whereby the ironoxid is reduced and part of the combustible gases is used up in removingthe oxygen from the iron oxid. The gases leaving the iron are -thenmixed with some oxygen or air and are passed into and burnt in thesecond regenerator, thereby raising its temperature. When the iron oxidhas been sufficiently reduced, steam is blown through the firstregenerator and then through theV cylinder containing the iron from thebottom to the top, whereupon hydrogen is produced. The period thusoccupied is short and in the meantime the second regenerator eitherretains its heat or, if desired, .it can be still further heated byburning fresh generator gas in it. The next period is filled up bypassing purified generator gas throughthe freshly heated secondregenerator, then, from above, through the vessel containing the ironoxid in order to effect its reduction, and then it is mixed with oxygenor air and is burnt in the first regenerator in order to raise itstemperature again. After this,steam is blown through thesecondregenerator vand into the cylinder containing iron, its direction beinupward, whereupon more hydrogen is pro uced and the iron is oxidized.The system has thus been brought into its original condition and thecycle of operations commences anew. If sufiiciently large regeneratorscapable of storing a large quantity of heat be made use of, "reducinggas and steam can be passed alternately in the same direction throughthe apparatus several times in succession until the regenerator which isgiving up heat to the reducing g'as and steam respectively has becometoo cool to heat up the reducing gas or steam sufficiently, whereuponthe gases are passed in the opposite direction through the apparatus.Such a.. method of working is obviously a modification of carrying outmy process and does not depart from the nature of my invention.

Apparatus suitable for carrying out the process of my invention isillustrated in the accompanying drawings. In these Figure 1 represents avertical section of the apparat-us and Fig. 2 is a plan view of thesame. Fig. 3 represents a View taken from above,

showing how four regenerators can be em# plo edin conjunction with onefurnace. Y

Siimilar letters and figures in the drawing refer to similar parts.

In the drawings, a, c, f, it, z', and 7c are regenerators, b and g arereaction furnaces, each being well isolated against loss of heat. Theregenerators comprise a combustion channel 1 and 21and a net work offireproof bricks 2 and 22,'the reaction mass being contained in theshaft 3 of the reaction furnace, while d and e are three-.way valves,capable of being cooled.

The method of working may be, for instance, as follows: The regeneratorsarefirst heated to ahigh temperature by burning in them a mixtureofgenerator gas or water-gas with air, while the waste gases` passthrough the valves8 and 9 into the chimney. As soon 'as the desiredtemperature isattained, one of the valves leading to the chimney, forinstance 8, is closed and, after opening valve 10, reducing gas is blownthrough the apparatus in the directions 2 1-12-14-18-3'-17-1321 22-9 or2-1--12`16-319-1513- 21-22-9, whereby the reaction mass in the furnaceis heated and reduced, an alternate passing of the gases'from above andfrom below through the furnace further causing t-he reaction mass toattain a fairly uniform temperature. The excess of reducing gases isthen mixed with the necessary amount of air from 5 and burnt in c. Whenthe temperature in the regenerator a diminishes, the gases are' passedthrough the apparatus 'in the reverse direction, that is to say, from 11to 8, so that the regenerator a. is again raised to a high temperature.If desired, however, the fall of temperature in the regenerator can beldiminished by adding a small quantity of air to the reduction gases,whereupon an the valve 23, so as to wash out the whole apparatus withsteam or hydrogen, preferably allowing the stear'n to enter the shaft 3of the reduclng furnace from above; the impure hydrogen which is formedis mixed with air from 5 and burnt in the combustion chamberv 21 of theregenerator. The three-way valve d is then so operated that the steampasses through 16 up into 3 and t-he valve 25 is opened and the valve 13is closed,v whereupon the hydrogen passes off.

in a pure state through 25 to the gasometer. When the oxidation periodis over, the reaction mass is reduced again as above described. Thevalves 4, 6, 7 and 24 are for use in supplying combustible gases, air,or steam to the regenerators to which they are respectively attached.If, after a series of oxidation and reduction periods, the temperatnrein a has sunk too low, the gases are passed in the reverse direction, sothat-@the regenerator c, which in the meantime h'as attained a hightemperature, gives up its heat to the reducing gasesand the steam, whilethe temperature of the other regenerator is being raised again byburning the excess of 'reducing gases therein, either alone or withfresh gas in addition.

The arrangement of regenerators with the common reducing furnace may beva.`

ried without departing from this invention; for example there may be acentral reducing furnace and two regenerators with suit-A ableconnections and three-Way valves, or

three or moreregenerators may be used ar-y ranged radially around areducing furnace, as shown for instance in Fig. 3.

Nowwhat I claim is: .l 1. The process of producing hydro Aen byalternately passing steam and a purified reducing gas over a ferruginousmass and passing the stea'm and the reducing gas be fore they enter thelreaction furnace through regenerators situated outside the furnace andpassing the reducing gas, after it leaves the said lfurnace, .inadmixture with oxygen, through one of the said regenerators, therebyraising the temperature of the said regenerator. l

2. The process of producing hydrogen by alternately passing steam and apurified reducing gas over a ferruginous mass and passing the steam andthe reducing gas before they enter the reaction furnace throughregenerators situated outside the furnace and passing the reducing gas,after it leaves the said furnace, in admixture with oxygen and othercombustible gas, through oneof the said regenerators, thereby raisingthe temperature ofthe said regenerator.

3. The cyclic process of producing drogen by passing purified reducinggas through a hot irst regenerator, then through a reaction furnacecontaining iron oxid, then adding oxygen to the gases leaving the saidfurnace and passing the mixed gases through a second regenerator, thenpassing steam through the first regenerator and then through lthefurnace, whereby the iron is oxidized and hydrogen is set free. thenpassing purified reducing gas through the second regenerator, thenthrough thel CARL BOSCH.

Witnesses J. ALEC. Lnorn, JOSEPH PFEIFFER.

